small measures with ashley: old window cold frame

Around my house, I’m always looking for ways to keep things out of the trash. Whether that means recycling, reducing or reusing objects in new ways, if it can stay out of the bin, I’m thrilled. Just as Kate’s new Treasure Hunting column shows ways of re-imagining items, I’m always trying to give new life to, or “upcycle,” what might otherwise be seen as waste. This intention is evident in my turning an unused metal gate from a dog crate into a rack for my earrings. It’s also manifest in my using cast-off marble headstones as benches around our outdoor fire pit (my home’s former owner worked part-time at a nearby cemetery, a cheeky bit of lore we always delight in sharing!).

In the spirit of keeping things in use (and out of the landfill), today’s Small Measures suggests repurposing old window frames in the form of a cold frame. As it’s name indicates, a cold frame is differentiated from a greenhouse, which is kept warm at all times. Consisting of a transparent cover, cold frames capture emitted sunlight and, as enclosed units, prevent the escape of heat. These devices permit a bit of a jump start on the growing season, and can be situated directly on the ground or, as is the case in my cold frame shown above, on a solid surface. — Ashley

Cold frames are typically placed against an existing heated structure. The residual heat from the home helps in capturing and maintaining heat inside the frame while simultaneously providing a wind break. As such, the air and soil temperatures within the structure will be several degrees higher than those in the exposed environment. While most cold frames are used to house seedlings that will later be transplanted into garden beds, some models are placed directly over soil and used to grow crops within them.

This past October, my husband and I finally got around to replacing some highly inefficient windows in our 1930s bungalow. We hung on to the old windows, intending to build a cold frame, which we finally did just the other day (the gorgeous warm weather we’ve been having here in western NC served as the prompt!). After screwing the windows into one another atop a plywood-sheet base, we topped the frame off with a piece of plexiglass found at a nearby building supply store. A bit of wood was added to create a pitch (for rainwater runoff), hinges were attached for opening the “doors” (we opted for cabinet-style front-entry doors, as opposed to a top entry), and knobs were affixed for ease of access. The entire frame was placed against our house on its south-facing side to optimize sunlight exposure and provide a buffer.

While the parameters of the frame I made were dictated by the measurements of the windows on hand, a similar model could easily be created using a window of any size. Architectural salvage stores and used building materials resale shops (such as Habitat for Humanity) are great sources for scoring old windows. Craigslist, Freecycle and local classified ads are other places to search. My frame was made with windows on all four sides to capture as much light as possible. It’s also customary to use wood panels on the sides (raised 1 to 2 feet off the ground) and to top off the frame with a window. You can see a version of one such model on this Instructables page.

If you’d like to grow crops in-ground using a cold frame, lettuces, spinach, carrots, radishes, parsley, chives and scallions all do remarkably well. If, like me, you intend to use the frame for starting seeds this spring, you can get a real leg up on growing warm-weather crops such as tomatoes, eggplant and peppers. Should temperatures take a serious dip, though, you’ll need to insulate your frame overnight using a heavy blanket or some burlap (see if local coffee roasters in your area would be willing to unload some of their burlap bags on you). Also, it’s important to vent the frame during particularly sunny days, otherwise your plants could be burned by the sun’s penetrating rays. This can easily be achieved either by using a wooden stake to prop open the top or by shimmying a wedge of wood under the cover. Just remember to close the frame back up in the evening.

What about you? Got any cold-frame wisdom to share? Repurposed-window tales to tell? I’d love to hear about it!

I love seeing useful things made from junk! LOL! My husband and I are looking at building a cold frame this spring so this will give us another option. The thing I like the best about it is it looks so vintage and it’s totally customizable! Thanks again! Great how-to!

heather-that wasn’t an issue with my windows, but if that is a concern with the windows you have, then, by all means err on the side of caution, especially if you intend to grow produce in-ground within the frame.

in that case, i’d say coat the interior of the frames with a new layer of (lead-free) paint, or seal them with a low-voc polyurethane. furthermore, we first used a wire brush on the frames to release any loose paint.

I just built a makeshift greenhouse from a rebar and cattle fence arbor that I had used for beans. I have posted about it on my blog, laughingorange.com. I have also been doing cold frame growing this winter for the first time and you can also see that progress on the blog. I got the inspiration from Eliot Coleman’s Four Season Gardening books where he grows greens year round in Maine. I love the old window idea and would love to upgrade my boxes to windows but have used plastic for now. Windows tend to be heavier, which can be somewhat of an issue but I would love the sturdiness after dealing with the plastic on windy days.

This isn’t really a cold frame, it’s more of a small greenhouse. Cold frames benefit from the insulation and thermal regulation of soil contact. Without soil below and around the glass, you are going to have high temperature fluctuations, when you are ideally trying to keep them constant. Seedlings do especially poorly in widely-varying temps.

My husband and I loved this idea…you inspired us to build a cold frame today. It turned out great! We had been thinking about doing something along the lines of a small greenhouse, but after seeing your post we decided a cold frame was a better idea. Thank you so much for sharing this with us!

I completely disagree Breanne. As Ashley mentioned, situating a cold frame against a house helps to regulate temperatures and can do so more effectively then the soil, which actually isn’t very good at regulating temperatures at the surface, making it not particularly good for seed starts. And since the soil against a house under the eaves is usually not an option for the base of a cold frame, Ashley’s design is particularly effective. But of course, build yours however you see fit.

What a timely post. Skip and I have been talking about building the exact same structure over a deep basement window well that gets southern and western light all day. Now I see how you did it I think we can get all of the windows from our Habitat Homestore.

A cold frame by definition is built low to the ground. What your husband built is cute but it isn’t really what you are calling it since it is on those legs. I think that person is right in that it won’t stabilize temps, you are very likely to get seedlings that are destroyed by heat or cold. I’ve been farming for 15 years and can promise this. You can always check with a thermometer during the day/night as compared with an real in-ground cold frame if you need to see for yourself :)

cold frames are indeed low to the ground most of the time, and even below the ground for people who want greater temperature regulation. the gardener for a world famous bonsai garden helped to design ours. for greater temperature regulation for the valuable bonsais, the ones that he works with are buried below the ground with cement walls.

what might not be clear from the photo above is that most of ours is sitting on a stone wall against our house, which has been doing a wonderful job of helping to regulate the temperature; perhaps better than many cold frames that sit on top of the ground, and perhaps not as good as those that are buried below the surface which does a lot to insulate.

our frame has plenty of ventilation, so overheating is not an issue where we live as long as we are on top of it. the wall that we had with southern exposure and a northern windbreak has a 16-inch stone wall sticking out about a foot and a half, so we worked with that, and are happy with the results.

as opposed to a standard greenhouse, a cold frame is only meant to take the edge off of the temperature by a few degrees (ideally 5 to 10) and we our happy with how effective our new cold frame has been in that regard so far.

for what it’s worth, a permaculture instructor was out here yesterday, and was actually very impressed with it. of course, by all means, people should use whatever works in the unique conditions of their living environment.

Design*Sponge reserves the right to restrict comments that do not contribute constructively to the conversation at hand, contain profanity, personal attacks, hate speech or seek to promote a personal or unrelated business. Our goal is to create a safe space where everyone (commenters, subjects of posts and moderators) feels comfortable to speak. Please treat others the way you would like to be treated and be willing to take responsibility for the impact your words may have on others. Disagreement, differences of opinion and heated discussion are welcome, but comments that do not seek to have a mature and constructive dialogue will not be published. We moderate all comments with great care and do not delete any lightly. Please note that our team (writers, moderators and guests) deserve the same right to speak and respond as you do, and your comments may be responded to or disagreed with. These guidelines help us maintain a safe space and work toward our goal of connecting with and learning from each other.